The present invention relates to a solid-state imaging apparatus which introduces light coming from an object into the inside of the apparatus, and photoelectrically converts an image of the object with a solid-state imaging device, as well as a camera using such a solid-state imaging apparatus.
The invention also relates to a camera in which a solid-state imaging device and IC chips and other electronic parts as its peripheral circuits are formed on one surface of a circuit board, and the one surface of the circuit board is covered with a light-shielding case having an opening for allowing light coming from an object to reach the solid-state imaging device, and which camera accommodates a lens for forming an image of the object on the front face of the solid-state imaging device.
Since the solid-state imaging apparatus is required to have superior electrical and optical characteristics, the solid-state imaging device as its heart needs to be incorporated in a special package that is high in mechanical accuracy. Further, the solid-state imaging device requires a very large number of peripheral circuits. For these reasons, conventionally, IC chips and other electronic parts as peripheral circuits are mounted on a printed circuit board that is completely separate from a package accommodating a solid-state imaging device. FIG. 1 is a block diagram showing a general configuration of a solid-state imaging apparatus. In FIG. 1, symbol CCD denotes a CCD solid-state imaging device; S/H, a sample-and-hold circuit; A/D, an A/D converter, DSP, a color signal processing unit; V. DRV, a V driver; TG, a timing generator; RAM, a random access memory connected to the color signal processing unit; and CONT, a microcomputer also connected to the color signal processing unit.
In the case of a digital apparatus, examples of peripheral circuits are a sample-and-hold circuit, a timing generator, a CCD solid-state imaging device clocked driver (what is called a V-driver, for instance), an AGC (auto gain control) circuit, a clock generator (a quartz oscillator, for instance), an A/D converter, a digital camera process circuit, a D/A converter, a composite TV encoder, a digital communication peripheral circuit such as IEEE 1394, FDDI, or a fiber channel, and a DC-DC converter.
In the case of an analog apparatus, examples of peripheral circuits are a sample-and-hold circuit, a timing generator, a CCD solid-state imaging device clocked driver (what is called a V-driver, for instance), an AGC (auto gain control) circuit, a clock generator (a quartz oscillator, for instance), a composite TV encoder, a DC-DC converter, and a camera process circuit, which are part of the above peripheral circuits of a digital apparatus.
FIG. 2 shows the configuration of a conventional solid-state imaging apparatus. In FIG. 2, reference numerals 51-53 denote a CCD solid-state imaging device, a lens unit, and a solid-state-imaging-device-mounting circuit board, respectively. A flexible circuit board 54 connects the solid-state-imaging-device-mounting circuit board 53 to an IC-mounting circuit board 55 made of glass epoxy resin, for instance. Numerals 56 and 57 denote ICs mounted on the circuit board 55 and a pin jack of the circuit board 55, respectively.
The conventional solid-state imaging apparatus shown in FIG. 2 cannot fully satisfy the requirement of miniaturization. Solid-state imaging apparatuses and cameras using those are used for a wide variety of purposes. For example, while the requirement of miniaturization is not so strong in cameras for business use such as a broadcasting purpose, it is very strong in cameras for home use. As the application range expands, the requirement of price reduction becomes more important in addition to the miniaturization.
However, it is difficult to reduce the size of the solid-state imaging apparatus of FIG. 2, because it requires the solid-state-imaging-device-mounting circuit board 53, the IC-mounting circuit board 55, and the flexible circuit board 54 for connecting the circuit boards 53 and 55 and each of those circuit boards occupies a non-negligible area. Further, due to the use of many kinds of circuit boards and a number of operation steps for connecting those circuit boards, the manufacturing cost of the imaging apparatus of FIG. 2 is high and hence there is a limitation in its price reduction.
FIG. 3 shows a conventional camera. In this camera, wiring films 152 are formed on one surface of a circuit board 151, and a solid-state imaging device 153 is mounted on one of those wiring films 152. IC chips 154 as peripheral circuits of the solid-state imaging device 153 are also mounted on the wiring films 152. A lens 155 is mounted on the same surface of the circuit board 151 by means of legs 156 of the lens 155 so as to have a given positional relationship with the solid-state imaging device 153. Further, a light-shielding case 157 for shielding the solid-state imaging device 153 and the IC chips 154 from the external environment is attached to the same surface of the circuit board 151.
Reference numeral 158 denotes an opening (aperture) formed in the light-shielding case 157. Light coming from an object is passed through the opening 158 and then imaged on the front face of the solid-state imaging device 153 by the lens 155. An optical filter 159 closes the opening 158. Further, reference numeral 160 denotes bonding wires; 161, resins formed by potting to seal the IC chips 154; and 162, an adhesive for bonding the leg 156 of the lens 155 to the circuit board 151.
The camera of FIG. 3 cannot fully satisfy the requirement of miniaturization. This is because, as described above, cameras using a solid-state imaging device are used for a wide variety of purposes. For example, while the requirement of miniaturization is not so strong in cameras for business use such as a broadcasting purpose, it is very strong in cameras for home use. Further, the requirement of miniaturization is strong in many of cameras for other purposes such as a monitor camera. On the other hand, cameras using a solid-state imaging device as its heart are required to be of high performance and have many functions and, resultingly, need to incorporate many peripheral circuits. The number of peripheral circuits needed is large particularly in the case of a digital camera.
A conventional solid-state imaging apparatus to be incorporated in an electronic camera or the like has a lens for forming an image of an imaging object.
FIG. 4 is a sectional view showing a conventional solid-state imaging device. A package 201 accommodates an imaging device (CCD) 203 to protect it from the external environment. The package 201 is formed with an opening for introducing imaging light, and the opening is covered with a cover glass 205. Leads 207 for leading out an electrical signal from the imaging device 203 are extended from the package 201. The leads 207 also serve to fix the package 201 to an inner surface of a case 209.
The case 209 is mounted with a lens 211 such that its optical axis is perpendicular to the cover glass 205. The lens 211 forms an image of imaging light coming from an imaging object on the imaging face of the imaging device 203. A lens stop 213, which is provided between the lens 211 and the cover glass 205 in the case 209, limits light coming from the lens 211 to adjust the amount of light reaching the imaging device 203.
The conventional solid-state imaging apparatus 215 having the above configuration can produces an electrical signal by forming an image of imaging light that is taken through the lens 211 on the imaging face of the imaging device 3 and photoelectrically converting the image.
However, in the above conventional solid-state imaging apparatus 215, which forms an image of imaging light by using the lens 211, the lens and the lens stop 213 for light quantity adjustment are needed. This results in disadvantages, i.e., a large number of parts and a complex structure, which are obstacles to miniaturization of the apparatus.
Since the lens 211, the lens stop 213, and the imaging device 203 need to be disposed on the optical axis with high accuracy, the imaging apparatus 215 is poor in ease of assembling. Further, since these parts need to be held so as to be kept highly accurate, it is difficult to handle the imaging apparatus 215.
The above problems are also factors of increasing the manufacturing cost of the imaging apparatus 215.